Mr. Kelly said he made the decision to commit the space to the article in October, not long after Mr. Langewiesche had begun reporting the piece.

Langewiesche was granted full access to the office coordinating the cleanup, and conducted extensive interviews with staff and officials involved in the effort.

"I thought it was a really remarkable opportunity to tell a really remarkable story," Kelly said.

"And if you're not going to give length to that, I don't know what you would."

The New Yorker, which also has a history of publishing long articles, is now running a two-part article from Caro that will go to 30,000 words. In 1993 it devoted a whole issue to a 53,000-word piece by Mark Danner called "Massacre and El Mazote."

But The New Yorker has run even longer articles. Truman Capote's "In Cold Blood" ran to 100,000 words and appeared over four issues.